Relevance of the expression “obs stable ” :

a retrospective study

Gregory Scott Academic clinical fellow

Roshan Vijayan Core surgical trainee

Pandora Male Medical student

Obs stable

Serious and important

BMJ

Seriousness

Quite silly and not important Christmas

BMJ

Importance

Should we seriously worry about what we write?

What’s wrong with “obs stable”?

1. “Stable” might be interpreted as “normal”

ButA patient with persistent tachycardia

has “stable” observations

2. “Obs stable” implies a lack of rigour

What do we even mean by “stable”?

Current obs within “normal” range?

Variation in obs within “normal” limits (L) for a given time period (t)?

t

L

Study• Objective: To ascertain whether use of the term “obs

stable” is so liberal as to render it meaningless.

• Design: Retrospective study

• Setting: Three London hospitals

• Methods– Searched notes for current admission of 46 randomly

selected inpatients for “obs stable” entries– Reviewed the nursing observations recorded during the

24 hours preceding each entry– Calculated for these 24 hour periods:

• Frequency of any abnormalities• Frequency of persistent abnormalities (occurring in every

observation)• Range (max.-min.) of observation values if at least two

observations had been recorded

Results: “obs stable” occurrences

– 1+ “obs stable” entry in 36 (78%) notes

– 178 “obs stable” entries total (3.9 per

patient)

– 1st “obs stable” entry on day 2 (median)

– 3.9 nursing observations charted in the

24 hours before each entry (SD 1.4)

Results: abnormalities in the 24 hours preceding “obs stable”

– 1+ abnormality in 113 (71%) of 159 cases• Tachypnoea (55%), hypotension (21%),

tachycardia (13%), desaturation (16%)

– 1+ one persistent abnormality in 31 (19%) cases

– Abnormality occurred in the observations immediately preceding an entry in 42% DefinitionsHypotension = SBP <100mmHg, Tachycardia = HR >100/minPyrexia = temperature >38C, Tachypnoea = RR≥20/minOxygen desaturation = saturations <95%

Results: all “stable” observations

Results: 24 hourly range of “stable” observations

Discussion: findings

• Doctors regularly used the expression “obs stable”

• “Obs stable” was often associated with a 24 hour period which included abnormal observations

• In two fifths of cases, an abnormality occurred in the observations immediately preceding an “obs stable” entry

• The range of observations over a 24 hour period that were designated “stable” occasionally exceeded normal values of diurnal variation

Discussion: limitations

• Small sample• No comparison with non-“stable” entries• Arbitrary definition of abnormalities• Arbitrary choice of 24 hour period• Difficult to define “normal” diurnal

variation

Discussion: why do we write“obs stable”?

• Lack of time given to documentation• Intended to be less committal• Observation chart design• The patient seems well

Conclusions

• The meaning of “obs stable” is ambiguous and does not always indicate normality.

• What could we write instead?–Write the observations in full – Qualify “obs stable” by adding “for the

last X hours” or– “Last abnormal observation was X

[observation] at Y [time]”• Perhaps obs stable has become ubiquitous

precisely because it of its ambiguity.

Thank you